養殖池排污方式與流場分布之關係研究

Studies on the Relationship Between the Emission of Sludge and Flow Fields in Aquaculture Pond

廖永豊(Yung-Li Liao)

指導教授 ： 侯文祥

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.00120

摘要

摘 要

養殖池業者使用各種曝氣方式於池中增氧，卻也一直困擾於底泥沉積物的管理。本研究實測嘉義與宜蘭兩地鰻池的流場造成與堆積物堆積速度實態，且與計算流體力學軟體模擬的流場結果比較，了解養殖池的流場造成法與堆積物分布關係。實測嘉義魚池槳式水車配置造成流場分布與底泥可能沉積位置，可給予改善建議。另針對宜蘭魚池使用之負壓式排污管，設計不同孔口數與孔口大小之六種孔徑比模組，探討孔口週邊的流場分布差異，並分析其吸除流量與文獻提出的負壓式排污建議流量之差異。

研究結果得知，養殖業者在給餌處之流場若為低流速區，需避免餌料沉積，造成飼料浪費及底泥堆積。嘉義鰻池水下60cm水層的流速小於0.17 m/s，水底流速則小於0.14 m/s區間，以水車前方速率為最高，之後遞減；水車後方也呈現遞減情形。

至於負壓式排污管的設計孔徑比以較小者為佳。實測得知管口最大吸除流速之孔徑比為0.38，最小吸除流速之孔徑比為3.04，其流速相差約2.5倍。將最小流速模組之管口自十個減至六個，其孔徑比由3.04變為1.82，管口吸除流速與孔徑比1.74模組相近，得知負壓式排污法之孔徑比為影響其管口吸除流速分布之主要因子。負壓排污管的基本模組中最佳模組為孔徑比為0.62，其管口處流速分布與距離管口遠近之負相關性R2值高達0.994。其排放量為105.1 gpm，與IDEQ(1998)文獻建議值100gpm以上相吻合。由本研究成果，未來可持續探討排水過程的固形物排污效率。

關鍵字

養殖池 ； 曝氣法 ； 排污法 ； 底泥 ； 計算流體力學

並列摘要

ABSTRACT

When the owners of aquaculture pond use various kinds of aerators to aerate the water, they encounter the difficulties in the management of sludge. By comparing the eel ponds experiments in Chiayi and Yilan, the sediment accumulation rate and hypothetical flow fields are confirmed with using the simulations of computational fluid dynamics (CFD). The framework of different positions of aerators and the hypothetical flow fields are built based on the experiments of trapped contaminated solids.

Advices are able to be given by knowing the sludge sediment area and the particle concentration flux. There are six aperture ratio models in different amounts and quantities of orifices of negative pressure discharge pipes that are designed for the eel ponds of Yilan. We discuss the differences in flow fields nearby the orifices, and then analyze the amount of water flow whether corresponds to the suggestion of negative pressure sewage.

The results have suggested that changing the feeding settling if the feeding sites are in low velocity area, in order to avoid it turns into sludge settling. The velocity under 60cm and from the water surface in Chiayi eel pond is less than 0.17m /s. The bottom velocity is less than 0.14 m/s. In front of the paddlewheels is the highest velocity and then decreases gradually and vice versa.

The aperture ratio of the negative pressure discharge pipes is better to be smaller. According to the investigation, the maximum velocity is 2.5 times difference between the aperture ratio being 0.38 and 3.04. The velocity of model which is reduced its orifices from ten to six is close to the model of aperture ratio being 1.74 from aperture ratio being 3.04 to 1.82. It is clear that the aperture ratio is the main factor to affect the velocity. The distance from the outflow department and velocity correlation in the model of aperture ratio is 0.62 R2 is 0.994 which brings out the conclusion that the velocity around the discharge pipes and the distance from the outflow department are in negative correlation. The amount of water flow of the negative pressure discharge pipes in Yilan is 105.1 gpm(gallons per minute) meets the suggestion that IDEQ(1998) proposed to be 100gpm. According to the achievement of this study, we can continue to investigate the experiments of collecting contaminated solids and discuss the efficiency of sewage.

並列關鍵字

Aquaculture pond ； Aeration ； Waste disposing ； Sediment ； Computational fluid dynamics

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